Optical alignment device for a table saw

ABSTRACT

A table saw includes a workpiece support surface and a laser apparatus. The workpiece support surface defines a blade opening through which a cutting blade is configured to extend. The laser apparatus is configured to emit a laser light away from the workpiece support surface.

This application is a continuation application of application Ser. No.13/081,791, filed on Apr. 7, 2011 (now U.S. Pat. No. 8,616,102), thedisclosure of such application which is totally incorporated byreference herein in its entirety.

FIELD

The present disclosure relates generally to power tools and particularlyto alignment devices for power tools.

BACKGROUND

Numerous power tools have been developed to facilitate forming aworkpiece into a desired shape. One such power tool for forming aworkpiece is a table saw. Table saws are typically used to cross-cut andrip-cut workpieces, such as hardwood, wood products, constructionlumber, and other materials.

Most table saws include a workpiece support surface and a cutting blade.The workpiece support surface is a generally planar surface on which auser positions the workpiece for cutting. The cutting blade, typically acircular saw blade, is mounted for rotation to an electric motor. Theelectric motor is positioned below the support surface. An upper portionof the blade extends above the support surface through a blade openingin the support surface. The narrow edge of the blade defines a cuttingpath.

An alignment device is included with most table saws to assist users inpositioning the workpiece relative to the cutting path of the blade. Onetype of alignment device is an indicium on the support surface thatidentifies the cutting path of the blade. A user cuts the workpiecealong a desired cut line by aligning the cut line with the indicium andthen directing the workpiece past the rotating blade. Another type ofalignment device is a laser positioning device, which projects a laserline onto the support surface. The laser line is aligned with thecutting path of the blade. To cut the workpiece along the cut line, auser aligns the cut line with the laser line and then directs theworkpiece past the rotating blade.

There exists a continuing need in the art to increase the accuracy andprecision of table saw alignment devices without increasing the cost andthe complexity of the devices.

SUMMARY

In accordance with one embodiment of the disclosure, there is provided atable saw including a workpiece support surface and a laser apparatus.The workpiece support surface defines a blade opening through which acutting blade is configured to extend. The laser apparatus is configuredto emit a laser light away from the workpiece support surface.

Pursuant to another embodiment of the disclosure, there is provided atable saw including a workpiece support surface, a light apparatus, anda reflective surface. The workpiece support surface defines a bladeopening through which a cutting blade is configured to extend. The lightapparatus is configured to emit a beam of light. The reflective surfaceis operably positioned to reflect the beam of light onto the workpiecesupport surface.

In accordance with yet another embodiment of the present disclosure,there is provided an optical alignment device for a table saw includinga laser apparatus and a reflective surface. The laser apparatus isconfigured for connection to the table saw and is configured to emit alaser light away from a workpiece support surface of the table saw. Thereflective surface is configured for connection to the table saw and isoperably positioned to reflect the laser light toward the workpiecesupport surface.

BRIEF DESCRIPTION OF THE FIGURES

The above-described features and advantages, as well as others, shouldbecome more readily apparent to those of ordinary skill in the art byreference to the following detailed description and the accompanyingfigures in which:

FIG. 1 shows a perspective view of a table saw;

FIG. 2 shows a cross sectional view of the table saw of FIG. 1 along theline II-II, with a light emitting apparatus associated with the tablesaw;

FIG. 3 is a diagram showing a method of operating the table saw of FIG.1; and

FIG. 4 shows a cross sectional view of the table saw of FIG. 1 along theline II-II, with an alternative embodiment of the light emittingapparatus.

DETAILED DESCRIPTION

FIG. 1 shows a table saw 100 configured to shape a workpiece. Exemplaryworkpieces that may be shaped with the table saw 100 includeconstruction lumber, hardwoods, building materials, and the like. Thetable saw 100 include a base 108, an enclosure 116, a table top 124, acutting assembly 132, and an optical alignment device (shown in FIG. 2).The base 108 is connected to the bottom side of the enclosure 116 and isconfigured to support the enclosure, the table top 124, the cuttingassembly 132, and the optical alignment device. The base 108 isconstructed of metal, rigid plastic, or the like. The base 108 includesfour ground-engaging legs; however, other configurations of the base arepossible.

The enclosure 116 defines an internal space, which houses variouscomponents of the table saw 100 including a portion of the cuttingassembly 132 and a portion of the optical alignment device. Theenclosure 116 is constructed of metal, rigid plastic, or the like, andis configured to support the table top 124.

The table top 124 is connected to the top side of the enclosure 116. Thetable top 124 is usually constructed of a rigid and generally flatmaterial such as metal, plastic, and/or fiberglass; however, the tabletop may also be constructed from other suitable materials. The uppersurface of the table top 124 defines a workpiece support surface 146,which supports a workpiece to be cut or shaped by the cutting assembly132. The support surface 146 defines a blade opening 150 through which aportion of the cutting assembly 132 (i.e. the cutting blade 164) isconfigured to extend.

As shown in FIG. 2, the cutting assembly 132 is configured to cut aworkpiece 156 positioned on the workpiece support surface 146. Thecutting assembly 132 includes a cutting blade 164, an electric motor(not shown) including a motor shaft 172, a riving knife 180, and a bladeguard 188. In the embodiment of FIG. 2, the blade 164 is a circular sawblade with cutting teeth or other cutting members. The particular typeof blade 164 is typically determined by the composition of the workpiece156 and the manner in which the workpiece is cut (i.e. rip-cut orcross-cut). The blade 164 defines a shaft opening through which themotor shaft 172 is configured to extend. The electric motor rotates themotor shaft 172 and the blade 164 about an axis of rotation 204 (FIG.1). The blade 164 is rotated in a clockwise direction, as illustrated inFIG. 2. The electric motor and the blade 164 are positionable relativeto the support surface 146 to enable the cutting assembly 132 to makebeveled cuts and cuts of a particular depth. The blade 164 is shown inFIG. 2 near a position of maximum cutting depth.

The riving knife 180 is positioned at the rear side of the blade 164 andis configured to prevent a kerf in the workpiece 156 from closing behindthe blade. The riving knife 180 is typically constructed of metal. Alower portion of the riving knife 180 is positioned below the supportsurface 146 and is coupled to the motor and the motor shaft 172.Therefore, the riving knife 180 moves with the electric motor and theblade 164 when the position of the blade is adjusted. Accordingly, theriving knife 180 does not interfere with cutting the workpiece 156 whenthe height and/or bevel angle of the blade 164 are adjusted by the user.In some embodiments, the riving knife 180 is referred to as a bladeguard support.

The blade guard 188 is configured to prevent objects from inadvertentlycontacting the blade 164. The blade guard 188 is movably connected tothe upper portion of the riving knife 180 and defines an internal spacein which the portion of the blade 164 above the support surface 146 ispositioned. The blade guard 188 is movable in any direction relative tothe support surface 146. Specifically, the blade guard 188 may be movedin a horizontal and/or a vertical direction relative to the supportsurface 146. The blade guard 188 may also be pivoted relative to theriving knife 180. Furthermore, the blade guard 188 may be moved relativeto the support surface 146 in a direction parallel to the axis ofrotation 204 of the blade 164. The blade guard 188 is typically formedfrom rigid plastic; however, the blade guard may also be formed frommetal such as aluminum and/or other materials.

With continued reference to FIG. 2, the optical alignment device isconfigured to strike a beam of light (or any other pattern of light)onto the support surface 146. The optical alignment device includes alight apparatus 212 and a reflective surface 220. The light apparatus212 is positioned below the support surface 146 and is mounted on themotor shaft 172. The reflective surface 220 is positioned above thesupport surface 146 and is mounted to the riving knife 180.

The light apparatus 212 emits the beam of light through the bladeopening 150 in the support surface 146. In the embodiment of FIG. 2, thelight apparatus 212 is a laser apparatus, and the beam of light is laserlight 228. In other embodiments, however, the light apparatus 212 emitsnon-laser light, as may be emitted by a light emitting diode (“LED”), afluorescent light source, or an incandescent light source. The laserlight 228 (or non-laser light) is emitted by the light apparatus 212 ina direction extending away from the support surface 146. In other words,the laser light 228 (or non-laser light) is emitted from the lightapparatus 212 in such a manner that, if not redirected, the light wouldnot strike the support surface 146. The reflective surface 220intercepts the laser light 228, such that reflected laser light 276 isdirected toward the support surface 146.

The light apparatus 212, in the embodiment of FIG. 2, includes a case236, a power source 240, a laser diode 244, and a lens 248. The case 236is formed from metal, plastic, and/or other suitable materials. The case236 has a generally toroid shape, which defines a shaft opening referredto as a central opening 252. The motor shaft 172 extends through thecentral opening 252. The diameter of the central opening 252 isapproximately equal to the shaft opening of the blade 164. A bolt (notshown), or other fastening member, is threaded into the end of the motorshaft 172 to connect the case 236 and the blade 164 to the motor shaft.Accordingly, the light apparatus 212 and the blade 164 rotate with themotor shaft 172 about the axis of rotation 204. The case 236 may bepositioned on the front side of the blade 164, as shown in FIG. 2, orthe rear side of the blade (not shown).

The case 236 is configured to withstand the forces imparted on the lightapparatus 212 due to the rotation of the motor shaft 172. These forcesinclude at least a centripetal force directed toward the axis ofrotation and a reactive centrifugal force in response to the centripetalforce. The case 236 maintains the relative positions of the power source240, the laser diode 244, and the lens 248 even when the motor shaft 172is rotating.

The power source 240 is connected to the laser diode 244 and isconfigured to supply the laser diode with electrical energy. The powersource 240 may be a battery. In other embodiments, the laser diode 244may receive electrical power from the power source that supplies theelectric motor with electrical power.

The laser diode 244 emits laser light 228 in response to beingelectrically connected to the power source 240. The laser diode 244 maybe selected based on a desired wavelength of the laser light 228.Exemplary laser diodes 244 may emit a laser light 228 that has a redcolor, a green color, or any other color that is suitable for viewing bya user.

The lens 248 receives and focuses the laser light 236 from the laserdiode 244 and emits the laser light radially with respect to the axis ofrotation 204. As shown in FIG. 2, the lens 248 focuses the beam of lightin a single line of light parallel to the cutting direction of the blade164. In other embodiments, however, the lens 248 focuses the beam oflight into a point of light on the workpiece 156 and/or the supportsurface 146. Similarly, lens 248 may focus the beam of light into apattern, which forms a pair of parallel lines on the workpiece 156and/or the support surface 146. The parallel lines may be positioned toidentify the cutting width of the blade 164. Still further, the lens 248may be configured to focus the beam of light into a grid pattern on theworkpiece 156 and/or the support surface 146. The grid pattern includesa first set of parallel lines and a second set of parallel lines, whichare orthogonal to the first set of parallel lines. The lens 248 may beformed from translucent materials including glass and certain plastics.The lens 248 may be interchangeable with other lens to enable selectionof the pattern of the beam of light. The lens 248 is configured to focuslaser light as well as non-laser light.

The lens 248 is illustrated in FIG. 2 at two rotational positions of thelight apparatus 212 as the light apparatus rotates with the motor shaft172. The laser light 228 emitted by the lens 248 when the lens is in thefirst position, is shown with a solid line, and strikes a bottom edge ofthe reflective surface 220. As the light apparatus 212 rotates about therotational axis 204 in the clockwise direction, the laser light 228continues to strike the reflective surface 220 until just after thelight apparatus is in the second position. In the second position thelaser light 228 is shown with a broken line, and strikes an upper edgeof the reflective surface 220. The lens 248 in the second position isshown with broken lines in FIG. 2. As the light apparatus 212 rotatespast the second position, the laser light 228 is emitted within theenclosure 116 until the lens 248 is in the first position again. Inanother embodiment, however, as the light apparatus 212 rotates past thesecond position, the light apparatus stops emitting the laser light 228until the lens 248 is in the first position again.

With continued reference to FIG. 2, the reflective surface 220 reflectsthe laser light 228 toward the support surface 146. The reflectivesurface 220 may be a glass mirror, a polished metal mirror, any othertype of mirror, or any other reflective surface. In one embodiment, thereflective surface 220 is a piece of adhesive tape having a reflectiveportion. Typically, the reflective surface 220 reflects the laser light228 (or non-laser light) onto the support surface 146 in a positionbased on the cutting path of the blade 164; however, otherconfigurations are possible. In some embodiments, the reflective surface220 has a curved shaped in order to focus the light from the lightapparatus 212 into a line of light. An exemplary curved shape is aparabolic shape.

In FIG. 2, the reflective surface 220 is an element of a reflectorapparatus 260 that is connected to the upper portion of the riving knife180 at a connection point 268. The reflector apparatus 260 is movable inany direction relative to the support surface 146 to enable positioningof the reflective surface 220 and the reflected laser light 276.Specifically, the reflector apparatus 260 is movable about a pivot axisthat is parallel the axis of rotation 204 and perpendicular to thedirection of the laser light 228. Accordingly, the position of thereflected laser light 276 may be adjusted in the direction 284 bypivoting the reflector apparatus 260. The reflector apparatus 260 alsoenables movement of the reflective surface 220 about a pivot axis 292,such that the reflected laser light 276 may be positioned in alignmentwith, closer to, or further from the cutting path of the blade 164.

The rotation of the light apparatus 212 by the electric motor causes thereflected laser light 276 to strike the reflective surface 220 for abrief time for each rotation of the motor shaft 172. However, the highrotational speed of the motor shaft 172 makes the reflected laser light276 appear to a user of the table saw 100 as a continuous line of laserlight. Accordingly, even though the laser light 228 is emitted from thelight apparatus 212 as a point of laser light, the light apparatusappears to impart a line of laser light onto the support surface 146 andthe workpiece 156. Additionally, the reflected line of laser lightappears to a user to have a relatively constant intensity even thoughthe laser light 228 is intermittently reflected onto the support surface146 and the workpiece 156.

In operation, the table saw 100 having the light apparatus 212 and thereflective surface 220 (referred to collectively as the opticalalignment device) simplifies the task of aligning a workpiece 156 withthe cutting path of the blade 164. The optical alignment device may beused according to the process 300 of FIG. 3. First, the power source 240supplies the laser diode 244 with electric power, which causes the diodeto emit laser light through the lens 248. Next or at the same time,electric power is supplied to the electric motor, which causes the motorshaft 172 to rotate the light apparatus 212 and the blade 164 about theaxis of rotation 204. In the block 308, during rotation of the lightapparatus 212, the light apparatus emits the laser light 228 through thelaser opening 252 and away from the support surface 146.

Next, in the block 316, the reflective surface 220 reflects the laserlight onto the workpiece support surface 146. The user of the table saw100 may rotate/pivot/move the reflective surface 220 about connectionpoint 268 and the axis 292 to position the reflected laser light 276 ina desired location. Typically, the user positions the reflected laserlight 276 in alignment with the cutting path of the blade 164.Alternatively, the user may position the reflected laser light 276 tostrike a laser line, which is a fixed distance from the cutting path ofthe blade 164.

In the block 320, after positioning the reflected laser light 276, whichappears as a line on the workpiece support surface 146, the user alignsa reference mark on the workpiece 156 with the reflected laser light.Specifically, when the workpiece 156 is placed on the support surface146, the reflected laser light 276 strikes the workpiece and is visibleas a line on the workpiece. The user moves the workpiece 156 to alignthe reference line with the reflected laser light 276.

Next in the block 328, the user cuts/shapes the workpiece 156 with therotating blade 164. The workpiece 156 is cut by moving the workpiecetoward the blade 164 until the workpiece passes the blade. The reflectedlaser light 276 strikes the workpiece 156 during the entire cuttingoperation to increase the accuracy and precision of cuts made with thetable saw 100.

The optical alignment device may be offered for sale in combination withthe table saw 100. Therefore, the consumer/end user acquires the opticalalignment device with the purchase or acquisition of the table saw 100.The optical alignment device purchased with the table saw 100 may bepre-installed by the manufacturer of the table saw 100 or installed bythe consumer.

Alternatively, the optical alignment device is purchased by the consumerin the aftermarket, as an accessory for an existing table saw (i.e. theoptical alignment device is available for sale without an accompanyingtable saw). Therefore, the consumer/end user may acquire the lightapparatus 212 and the reflective surface 220 for use with an existingtable saw. The light apparatus 212 may be used with any existing tablesaw having a motor shaft that is receivable by the opening 252. Thereflective surface 220 may be used with any table saw having a fixedelement positioned above the workpiece support surface. The lightapparatus 212 emits the laser light from below the support surfacethrough the blade opening if an independent laser opening is notincluded in the support surface of the table saw. Accordingly, theoptical alignment device provides cost savings compared to other opticalalignment devices, which are designed for use with only a single tablesaw.

Another embodiment of the optical alignment device for use with thetable saw 100 is shown in FIG. 4. For clarity, like components shown inFIG. 4 and FIG. 2 are labeled with like reference numerals except thatthe reference numerals in the embodiment shown in FIG. 4 include a primesymbol (′). In this embodiment, the reflector apparatus 260′ isconnected to the blade guard 188′, and the light apparatus 212′ isconnected to the riving knife 180′. Accordingly, the light apparatus212′ is not configured for rotation relative to the motor shaft 172′ andthe blade 164′. Instead, the light apparatus 212′ remains stationaryduring operation of the electric motor and rotation of the blade 164′.The light apparatus 212′ includes a lens 248′ that emits a line of laserlight 324′ away from the support surface 146′. The line of laser light324′ passes through a light opening 232′ in the support surface 146′.The light opening 232′ and the blade opening 150 are separate anddistinct openings in the table top 124. The reflective surface 220′reflects the line of laser light 324′ (reflected line of laser light330′) onto the support surface 146′ and the workpiece 156′. The laserlight 324′ may be reflected in a position based on the cutting path ofthe blade 164′.

The light apparatus 212 of FIG. 2 may be configured for use with thereflector apparatus 260′ and the reflective surface 220′ shown in theembodiment shown in FIG. 4. Additionally, the light apparatus 212′ ofFIG. 4 may be configured for use with the reflector apparatus 260 andthe reflective surface 220 in the embodiment shown in FIG. 2.

In another embodiment of the table saw 100, the light apparatus 212 andthe reflective surface 220 are positioned above the support surface 146.In this embodiment, the light apparatus 220 may be connected to aportion of the riving knife 180 positioned above the support surface146. Alternatively, the light apparatus 212 may be positioned within theblade guard 188, such that both the light apparatus 212 and thereflective surface 220 are positioned within the blade guard 188.

In yet another embodiment of the table saw 100, the light apparatus 212is positioned above the support surface 146 and outside of the boundarydefined by the table top 124 (i.e. outside of the footprint of the tabletop 124). In particular, the light apparatus 212 is connected to asupport structure (not shown), which is connected to the table top 124or the enclosure 116 and positions the light apparatus 212 beyond theboundary defined by the table top 124.

With reference again to FIG. 1, it is noted that some embodiments of thetable saw 100 do not include the base 108. These embodiments of thetable saw 100 may be referred to as portable table saws, jobsite tablesaws, bench-top tools, and semi-stationary tools. The enclosure 116 of atable saw 100 without a base 108 is configured for placement on a workstand. The light apparatus 212 and the reflective surface 220 areconfigured for use with any type of table saw.

Although a table saw has been described with respect to certainpreferred embodiments, it will be appreciated by those of skill in theart that other implementations and adaptations are possible. Moreover,there are advantages to individual advancements described herein thatmay be obtained without incorporating other aspects described above.Therefore, the spirit and scope of the appended claims should not belimited to the description of the preferred embodiments containedherein, and the claims, as originally presented and as they may beamended, encompass variations, alternatives, modifications,improvements, equivalents, and substantial equivalents of theembodiments and teachings disclosed herein, including those that arepresently unforeseen or unappreciated, and that, for example, may arisefrom applicants, patentees, and other.

What is claimed is:
 1. A table saw comprising: a workpiece supportsurface defining a blade opening through which a cutting blade isconfigured to extend; a rotating laser apparatus positioned below theworkpiece support surface and configured to emit a first laser beam; anda reflective surface positioned above the workpiece support surface andconfigured to intermittently reflect the first laser beam toward theworkpiece support surface.
 2. The table saw of claim 1 wherein thereflective surface is configured to intermittently reflect the firstlaser beam onto the workpiece support surface at a location indicativeof a cutting path of the cutting blade.
 3. The table saw of claim 1,further comprising: a riving knife having an upper knife portionpositioned above the workpiece support surface and a lower knife portionpositioned below the workpiece support surface; and a blade guardconnected to the upper knife portion of the riving knife, wherein thereflective surface is connected to one of the upper knife portion andthe blade guard.
 4. The table saw of claim 1, wherein the rotating laserapparatus emits the first laser beam intermittently through a laseropening in the workpiece support surface.
 5. The table saw of claim 1,wherein: the cutting blade is configured to rotate about a rotationalaxis, and the laser apparatus is configured to rotate about therotational axis.
 6. The table saw of claim 1, wherein the reflectivesurface is configured to reflect the first laser beam as the laserapparatus is rotated through an arc.
 7. The table saw of claim 6,wherein the laser apparatus is configured to emit a second laser beamspaced apart from the first laser beam.
 8. The table saw of claim 7,wherein the reflective surface is configured to intermittently reflectthe first laser beam and the second laser beam onto the workpiecesupport surface to form two parallel line segments of reflected laserbeams which identify a cutting width of the cutting blade.
 9. A tablesaw comprising: a workpiece support surface defining a blade openingthrough which a cutting blade is configured to extend; a rotating lightapparatus positioned below the workpiece support surface and configuredto emit a first beam of light; and a reflective surface positioned abovethe workpiece support surface and configured to intermittently reflectthe first beam of light onto the workpiece support surface.
 10. Thetable saw of claim 9 wherein the reflective surface reflects the firstbeam of light intermittently onto the workpiece support surface at alocation indicative of a cutting path of the cutting blade.
 11. Thetable saw of claim 9, further comprising: a riving knife having an upperknife portion positioned above the workpiece support surface and a lowerknife portion positioned below the workpiece support surface; and ablade guard connected to the upper knife portion of the riving knife.12. The table saw of claim 11 wherein: the reflective surface isconnected to one of the upper knife portion and the blade guard.
 13. Thetable saw of claim 9 wherein: the cutting blade is configured to rotateabout a rotational axis perpendicular to a direction of the beam oflight; and the reflective surface is movable about the rotational axis.14. The table saw of claim 13 wherein: the light apparatus is configuredto rotate about the rotational axis.
 15. The table saw of claim 9,further comprising: a motor shaft, wherein the cutting blade defines afirst shaft opening through which the motor shaft is configured toextend and the light apparatus defines a second shaft opening throughwhich the motor shaft is configured to extend.
 16. The table saw ofclaim 9, wherein the reflective surface is configured to reflect thefirst beam of light as the light apparatus is rotated through an arc.17. The table saw of claim 16, wherein the light apparatus is configuredto emit a second beam of light spaced apart from the first beam oflight.
 18. The table saw of claim 17, wherein the reflective surface isconfigured to intermittently reflect the first beam of light and thesecond beam of light onto the workpiece support surface to form twoparallel line segments of reflected light beams which identify a cuttingwidth of the cutting blade.